Six Decades of Growth and Yield and Financial Return in a Silviculture Experiment in Northern Hardwoods

The Cutting Methods Study at the Ford Forest in the Upper Peninsula of Michigan, USA, was established in 1956 and has been maintained continuously on a 10 year cycle. Methods consist of three diameter limits (DL; 13, 30, and 41 cm), single-tree selection to three residual basal area limits (STS; 11, 16, and 21 m2ha−1), and light improvement (LI) focused on improving tree grade. Long-term results show that the 41 cm DL produced the greatest managed forest value and cumulative sawlog production, followed by the STS to 11 m2ha−1 residual basal area. STS treatments and LI were uniformly superior at improving standing tree grade. In contrast, treatments that emphasize removal of large diameter trees while retaining moderate residual basal area (the 41 cm DL and 11 m2ha−1 STS) produced the largest harvest volumes of high-grade sawlogs, driving financial performance. Stand density has declined in all treatments except the 30 and 41 cm DL, where it has increased, and these two treatments have larger abundance of saplings and poles. Alternative partial cutting methods such as selection to lower residual basal areas and medium-intensity diameter-limit cuts thus may provide greater financial returns and higher average quality, and could have implications on regeneration and long-term sustainability. Study Implications: Long-term comparison of alternative partial cutting practices in northern hardwoods in the Upper Peninsula of Michigan over 60 years reveals that Arbogast-based single-tree selection is inferior using financial and volume yield criteria. Alternatives that remove more of the larger trees appear over time to increase regeneration and harvested tree quality, which in turn drives financial performance. However, treatments with extremely high volume removals perform poorly against all others, and have few, if any, redeeming financial, silvicultural, or ecological qualities.

Two for One: Conservation of Aquatic Ecosystems With Buffers Protects Terrestrial Ecosystems

We evaluated how three widths of buffer zones on greater than or equal to 100-ha wetlands (240, 300, and 390 m) and rivers (10, 20, and 30 m) would help meet watershed conservation goals in the Upper Peninsula of Michigan, USA, and whether doing so also would protect each of the predominant types of terrestrial natural communities across the landscape. The use of buffer zones (even the narrowest widths assessed) around wetlands and riparian zones met or exceeded conservation targets in 75% of watersheds and greater than or equal to 85% of subwatersheds evaluated. Wetlands and riparian zones with buffers captured each of the predominant types of terrestrial natural community in Michigan's Upper Peninsula, but not proportionately to their availability across the entire landscape. Our work demonstrates that a landscape-conservation approach focused on wetlands and riparian zones with buffers can conserve terrestrial, wetland, and riparian ecosystems across Michigan's Upper Peninsula and may also be applicable in other areas where mapping of wetlands and rivers occurs.